Initial relaxation of spatially evolving turbulent channel flow with blowing and suction

Abstract

A direct numerical simulation is performed to examine the initial relaxation of spatially,evolving turbulent channel flow subjected to uniform wall blowing and suction. Just beyond the entrance section, a uniform blowing is applied at the lower wall and a uniform suction at the upper. The relaxation processes of the mean velocity, turbulence intensities, Reynolds shear stresses, and vorticity fluctuations after the sudden wall blowing and suction are scrutinized. The effect of wall blowing and suction on the location and strength of the streamwise vortices is significant. The relaxation associated with suction is much slower than that with blowing. The initial relaxation is evaluated in terms of the turbulent kinetic energy transport. Blowing enhances the intercomponent energy transfer between the Reynolds stresses, whereas suction suppresses it.